Impulse starter



K. H. MRCK.

IMPULSE STARTER.

APPLlcATloN FILED 1AN.6.1919.

Patented Feb. 21, 1922.

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ffy-fanny? K. H. MRCK.

y |=MPULSE STARTER.

APPLICATION FILED mn. e, 1919.

1,407,077, Patented Feb. 21, 1922.

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K. H. MRCK.

lVlPULSE STARTER.

APPLICATION man 1AN.6,1919.

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2y M M IN2/F77 UNITED STATES PATENT OFFICE.

XNUT H. MRGK, O1? BUFFALO, NEW YORK, ASSIGNOR, BY MESNE ASSIGNMENTS, TO

ERICSSON MANUFACTURING COMPANY7 OF BUFFALO, NEIN YORK, A CORPORA- TION OF NEW YORK.

T 0 all whom t 'may concern Be it known that I, KNUT H. Mnon, a subject of the King of Sweden, residing at Buffalo, in the county of Erie and State of New York, have invented new and useful Improvements in Impulse Starters. of which the following is a specification.

This invention relates to the driving mechanism used in connection with the ignition inagnetos of internal combustion engines, and more particularly the type of driving devices commonly known as impulse starters.

An ignition magneto equipped with such an impulse starter formsa simple, self-contained ignition unit which iscapable of sierving as the sole ignition means on any type of internal' combustion engine. It is, however, particularly desirable for the engines of farm tractors as it ensures an efficient spark for starting the heavy engine, but without adding unduly to the cost of manufacture or complicating they simple, self-contained magneto ignition system and without requiring eXtra electrical or mechanical skill or knowledge on the part of the operator.

Farm tractors and analogous machines are operated under unusually severe conditions and subjected to rough usage, being Yexposed to dust, mud, water, heavy strains and vibrations. They are alsol liable to abuse and neglect at the hands of unskilled operators.

It isthe principal object of my invention to provide an impulse starter of simple and durable construction which is capable of meeting the most severe conditions of operation and which is positive and reliable in action under all circumstances.

lFurther objects are the provision of a starting device of this kind which is entirely automatic in action, which is compact in con struction, and has large well-lubricated wearing surfaces and in which all working parts are fully protected from mud, dust and moisture by an oil-proof case formed by the body of the impulse-starter itself.

kIt is Qa further object of the invention to provide automaticmeans whereby the speed at which the impulse starter ceases to give -a series of rapid semi-revolutions to the magneto'arniature shaft, shall be determined and maintainedwithin narrow limits and whereby this critical speedv shall depend solely on the action of centrifugal force and in no wayA on rebound, or bumping`action of any of the'pa'irtsf-Vl l w Specification of Letters Patent.

Application ied January G, 1919.

Patented Feb. 21, 1922.

semi No. 269,731.

In the accompanying drawings:

Figure 1 is a sectional elevation of an impulse starter, constructed in accordance with iiiy invention and `shown in connection with a magneto and suitable coupling means to an engine drive shaft. Figures 2, 8 and i are cross sections on line A-A, Fig. 1, showing the relative positions of the parts under different conditions. Figure 5 is a top plan view of the stop-plate secured to the inagiieto frame. Figure 6 is a front elevation thereof. Figure is a cross section on line B-B, Fig. 6. Figure 8 is a front elevation of the reciprocating pawl. Figure 9 is a cross section thereof on line C-C, Fig. Si. Figure 10 is a rear view of the magneto driving-plate of the impulse starter. Figure 11 is a transverse section thereof on line D--D` Fig. 10. Figure 12 is a front elevation of said plate. Figure 13 is a rear or inside view of the starter housing. Figures 1/1 and 15 are cross sections on line E413, Fig. 13 viewed in opposite directions.

Similar characters of reference indicate corresponding parts throughout the several views.

1 indicates the frame of the magneto and 2 the tapering end portion of the armature shaft. Mounted on this shaft and keyed or otherwise secured thereto is the hub 3 of a driven plate or disk 4 which is clamped in place by a nut 5 and an interposed washer 6. 7 indicates the case or housing of the impulse starter which encloses its several parts and which is rotatably supported on the driven plate l, preferably by a hub 8 eX- tending inwardly from the housing and journaled in a sleeve or bearing 9 extending outwardlv from the driven plate. In the construction shown, the hub 8 is arranged within the said bearing sleeve. Any suitable means may be employed for holding the housing against endwise displacement, the device rshown in the drawings for this purpose comprising an inwardly-turned lip 10 formed at the inner end of the housing-hub and confined between the outer side of the driven plate and the projecting edge of the washer 6. y

11 indicates the driving shaft of the moitor or engine from which motion is transmitted to the rotary housing by a suitable coupling. In the construction shown, the liousingis provided at its outer end with the usual projecting lugs 12 with which correspending parts 13 of the coupling head 14 interlock, this head being keyed or otherwise secured to the driving shaft. On' its upper side, preferably opposite the bearing 9, the housing is provided with an oil cup 15.

Located in the portion of the housing in rear of the driven'plate 4 is a pawl or reciprocating paWl-member 16 which is connected with said plate by a pair of studs or pins 17, 18, projecting rearwardly therefrom on opposite sides of its hub and engaging slots or notches 19, 20, formed centrally and longitudinally in the adjacent portion of the pawl. This pin-and-slot connection, while permitting the pawl to reciprocate on said driven plate, compels the latter to rotate with the paw'l. The pawl is thickened or weighted at its wide outer end, as shown at 21, and in the outer edge of this thickened portion it is provided with a clutch notch 22 adapted to interlockwith a corresponding internal clutch-tooth 23 carried by the rim of the housing 7 when the pawl is thrown out against said rim by centrifugal force under normal or high-speed of the driving shaft. Under a slow or starting speed of said shaft, the pawl on reaching the upper side of the magneto shaft drops by gravity to a. position in'which its notch 22 is out of engagement with the clutch tooth 23 of the housing. In its preferred form, the pawl-member is yoke-shaped and surrounds the hub 3 of the driven plate 4. At the inner edge of its wide portion, the pawl is provided with a tooth 24 which in the retracted position of the pawl is adapted to encounter one of a pair of stops or teeth 25 carried by a plate 2G fixed to the adjacent portion of the magneto frame by screws 27 or other suitable means. In the construction shown, these teeth are formed by the lateral edges of an approximately semi-circular collar or sleeve 28 projecting from the front-side of said stop plate. The pa-wl tooth` 24. is adapted' to engage one or the other of these stop-teeth, according to its direction ofjrotation, so as to temporarily stolp the rotation ofthe driven pla-tell.

i rranged on the inner side of the housing rim in line with the pawl is a. releasingmember or cam 29 adapted to engage the small end of the pawl, when the latter gravitates to its retracted' position, so as to trip the pawl loutof engagement with the coopera-tmg toothof the stop-plate 26 and allow the pawl and the driven plate torotate Without restraint. i Y

indicates a comparatively strong coilspring arranged in the annular space between. the sleeveI 9. and lthe surrounding housing andl bearing at its endsagainst internal stop blocks or abutments 31',- 32,-xed'to-the opposing sides of the housing and the driven plate, respectively, whereby said spring is compressed byV rota-tionr of thev housing` relative to said plate. This spring may be of any other suitable construction, if desired.

A buffer or rebound spring .f 3 is arranged on that side of the sleeve 9 opposite. the main springv 30 and interposed between the opposing ends of said abutments.

The front end of the housing is closed, preferably by an integral head, as shown, while its rear or inner end is closed by a removable plate or cover 3-1 which bears against a packing 35 of felt or other suitable material surrounding the collar 28 and seated in an annular groove 36 in the face of the stop-plate 26. This cover may be held in place by any appropriate means, such as a split ring 37.

The operation ofthe impulse starter is as follows:

Supposing the engine to be running above cranking speed, the relative positions of the parts of the starter are as shown in Figs. 1 and 2, the slidable pawl 1G beingheld at the outer extremity of its stroke by centrifugal force. The clutch notch 22 of the paw-l therefore interlocks with? the clutch tooth 23 f the housing and the motion of the driving shaft 11 `is transmitted to the armature shaft of the-magneto through the pawl and the driven plate 4. The armature shaft is thus driven uniformly with the housing, and under these conditions the impulse starter acts simply as a coupling between said shafts.

lVhen, however, the engi-ne is running slowly, as iii-cranking it by hand, for example, the pawl, when its weightedv end comes uppermost, gravitates toward the center of the housing as far as permitted by the stud 17 working in the closed slot 19, thereby dise engaging the pawl from said clutch tooth and bringing th'epa wl-tooth 24 into the path of the opposing tooth of the stop plate 26. The forward motion of the housingis however still transmitted to the driven plate 4 through the strong main spring 30` which is compressed between the abutments 31, 32 of said parts. This driving action through said spring continues until the toothof the paw] encounters the stop-tooth 25, when said driven plate is suddenly arrested and said spring is further and strongly compressed by the continued forward rotation-olf the housing which causes the abutment of the latterto more closely approach the temporarily stationary abutment carried by the driven plate. Whenthe housing, after an angular travel of approximatelyv sixty de grees from the position shown in Fig 3, amrives near the 'position'show'ri in Fig.. 4, itl cam 29 rides over the-adjacent smallend of the pawl, forcing the latter toward the opposite side of the housing, disengaging itsbootli 24 from the tooth of the stop plate and N- leasing the driven plate. Theila'tter thereupon receives .a powerful forwardimpulse by the recoil of the compressed spring 30 which is imparted to the armature shaft,

producing a powerful current impulse and a correspondingly strong ignition spark.

As the engine begins to fire and continues to turn, the above-described action of the starter is repeated at each revolution until a predetermined speed, say 120 revolutions per minute, is attained, at which speed centrifugal force overcomes the weight of the pawl and again throws it to its outermost position in which it automatically interlocks with the housing and clears the teeth of the stop plate 26. The driven plate is therefore no longer lperiodically stopped, released and snapped forward, but it and the armatureshaft are driven uniformly with the housing.

After the driving plate has been stopped and released, as above described, its resultant rapid forward movement is arrested by the rebound spring 38.

It will be noted that the pawl and the cooperating stop teeth 25 are located inside the housing, close to the hub 3 of the driven plate, while the collar 28 which carries said teeth, telescopes over said hub, leaving only a small running clearance between these parts. This construction and arrangement affords the following advantages:

The working mechanism of the starter is all enclosed in a strong steel case, and with a running joint of small diameter between the magneto and the starter, in the form of a felt washer fitting against the end cover of the case. The starter, therefore. takes the form of a rotating round box which is dust, water and oil tight, and with the mechanism as well protected as if it were enclosed in a stationary case.

The absence of stops or other parts outside of the starter casing allows such a diameter of the casing that it revolves close to the base of the magneto. This comparatively large allowable diameter of the casing brings the center of gravity of the pawl a comparatively longl distance from the center of rotation. Therefore centrifugal force acts powerfully and positively to hold the pawl tooth out of engagement with the stationary stop tooth at any pre-determined low speed at which it is desired that the device shall cease operating as an impulse starter. There is, moreover, no rebound or jumping of the pawl and stop-teeth with the accompanying uncertainty of action.

Since the pawl tooth is located on that part of the pawl which, inthe construction shown, is three plates thick, the pawl and stop teeth which take the strain and wear incident to stopping the armature and compressing the main spring, are of the full width of the widest portion of the pawl and therefore of ample strength for severe service. As the distance from the center of rotation to the point of impact of the pawl and stop teeth is comparatively short, the teeth strike at a comparatively low velocity with a less forcible blow.

Since the stop-lock plate as a whole is concentric with the armature shaft and its sleeve portion is of comparatively small diameter, it is a simple matter to provide for any necessary angular shift of said plate to accommodate the starter to any magneto and to either direction of rotation.

I claim as my invention:

l. The combination with the shaft of an electric generator, of a driven plate fixed to said shaft, means for retaining said plate on said shaft, said driven plate having a bearing-sleeve on its outer side, a relatively fixed stop, a pawl-member carried by said plate and adapted to engage said stop, a driving case enclosing said plate and said pawl member and having a hub journaled in said sleeve and provided with a lilp interlocking with said plate-retaining means, a spring interposed between said plate and said case, and releasing means for said paWl-member carried by said case.

2. An impulse starter, comprising a relatively fixed plate having a stop, a driven plate adapted to be fixed to an electric generator-shaft, a pawl-member carried by said driven plate and adapted to engage said stop, a rotatable housing enclosing said driven plate and said pawl-member, a spring interposed between said housing and said driven plate, releasing means for said pawlmember carried by said housing, a cover closing the inner end of said housing, and a packing interposed between said cover and said fixed plate.

KNUT H. MRCK. 

